Current Load on the Triboelectric Properties and Wear Mechanisms of Gold-plated Copper Alloy Pairs

In order to investigate the current-carrying tribological properties and wear mechanisms of gold-plated copper alloy pairs under high electric current conditions based on high-power electrical connectors, the reciprocating sliding current-carrying friction tests were carried out under different electric currents (with current density up to 26 A/mm²) selecting a ball/plane contact pair composed of gold-plated brass and beryllium copper alloy in this work. Experimental results showed that under 0 A condition, the friction coefficient was relatively high and with electric current flowing through, the friction coefficient decreased. As the current increased from 5 A to 20 A, the friction coefficient gradually increased and the fluctuation of friction coefficient decreased. The surface roughness of the wear mark also increased, with its relative value higher than 600% compared with the unworn sample when the current above 15 A. The wear rate also increased with the increasing current, while the value turned negative at 20 A indicating that the sample volume increased due to the interface material transferring. As for electrical properties, the contact resistance and its fluctuation value both decreased as the current increasing. In summary, with the current increasing, the frictional and wear performances degraded and the quality of contact surface deteriorated, but the electrical contact properties improved. As for wear mechanisms, furrows and plastic deformations dominated at relative lower currents (5 A and 10 A), while adhesive wear made a great contribution at relative higher currents (15 A and 20 A). The calculational results demonstrated that that Joule heating power was much larger than the frictional heating power, which dictated the interfacial temperature rise. And the maximum temperature of the contact interface was 78.0 ℃ at 20A obtained by finite element calculation. Therefore, the temperature rise due to Joule heating led to material softening, resulting in the contact area increase, and thereby causing the rise of friction coefficient and the decrease of contact resistance. On the other hand, the strength decreased after material softening, which promoted adhesive wear. This study was expected to provide theoretical support for the material design and damage protection of the contact pair in high-power electrical connectors.